The present invention relates to refill units for windshield wiper blades and, more particularly, to improvements in retaining the refill unit in assembly with the superstructure to allow accomodation to diverse types of superstructures.
Among the several known designs for retaining refill units in assembly with windshield wiper blade superstructures are end clips similar to that shown in U.S. Pat. No. 3,153,254 to Lenz et al issued Oct. 26, 1964; claw embracing notched rails as shown in U.S. Pat. No. 3,141,186 to Scinta issued July 21, 1964; deflection of superstructure to align notch in rail of refill for removal or installation as shown in U.S. Pat. No. 3,408,680 to Heller issued Nov. 5, 1968. More relevant to the present invention are the claw embracing clips shown in U.S. Pat. No. 3,952,360 to Plisky et al issued Apr. 27, 1976 and a clip illustrated on the Fram Corporation, Providence, R.I. carton for wiper blade refills.
These prior art refill retaining elements and others which have been proposed and used are either designed for a specific superstructure or require the stocking of several different types of refills to accomodate the many different superstructures currently in use. The refill unit is an expendible element which can be replaced when the squeegee element is worn out without having to replace the entire windshield wiper blade. Superstructures vary from full length extending over substantially the full length of the blade to short in which the ends of the refill unit extend substantially beyond the inboard and outboard claws. There are triple yoke type, stacked lever and end to end levers. The pairs of opposed claws may be laterally and longitudinally spaced apart different distances. There are plastic and metal superstructures. Therefore the advantage of a universal refill that can accomodate all or at least most of the different superstructures now in use is readily apparent.